Approximate Aeroelastic Modeling of Flapping Wings in Hover
19 Feb 2013-AIAA Journal (American Institute of Aeronautics and Astronautics)-Vol. 51, Iss: 3, pp 567-583
TL;DR: In this article, a nonlinear aeroelastic model suitable for flexible insect-like flapping wings in hover is presented by coupling a structural dynamic model based on MARC, with a potential-flow-based approximate aerodynamic model that consists of leading-edge vortices and a wake model.
Abstract: A nonlinear aeroelastic model suitable for flexible insectlike flapping wings in hover is presented. The aeroelastic model is obtained by coupling a nonlinear structural dynamic model based on MARC, with a potential-flow-based approximate aerodynamic model that consists of leading-edge vortices and a wake model. The aeroelastic response is obtained using an updated Lagrangian method. The paper describes validation studies conducted on the structural dynamic model, aerodynamic comparisons, and aeroelastic studies conducted on isotropic and anisotropic Zimmerman wings. The results demonstrate the suitability of MARC for modeling anisotropic wings undergoing insectlike wing kinematics. For the aeroelastic cases considered, the approximate model shows acceptable agreement with computational-fluid-dynamics-based and experimental results. The approximate model captured several important trends correctly.
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TL;DR: The solution of the boundary layer tracking problem proposed in this paper can be described as an ALE implementation of a given EBM for CFD, which is simple and computationally reasonable.
73 citations
TL;DR: In this paper, the influence of kinematic parameters such as the percentage overlap between translational and rotational phase ξ, the separation between two wings δ and Reynolds numbers Re on the evolvement of lift and drag has been investigated.
Abstract: The present study focuses on the analysis of the fluid dynamics associated with the flapping motion of finite-thickness wings. A two-dimensional numerical model for one and two-winged “clap and fling” stroke has been developed to probe the aerodynamics of insect flight. The influence of kinematic parameters such as the percentage overlap between translational and rotational phase ξ, the separation between two wings δ and Reynolds numbers Re on the evolvement of lift and drag has been investigated. In addition, the roles of the leading and trailing edge vortices on lift and drag in clap and fling type kinematics are highlighted. Based on a surrogate analysis, the overlap ratio ξ is identified as the most influential parameter in enhancing lift. On the other hand, with increase in separation δ, the reduction in drag is far more dominant than the decrease in lift. With an increase in Re (which ranges between 8 and 128), the mean drag coefficient decreases monotonously, whereas the mean lift coefficient decreases to a minimum and increases thereafter. This behavior of lift generation at higher Re was characterized by the “wing-wake interaction” mechanism which was absent at low Re.
42 citations
TL;DR: The results of this study show that the trim conditions of insect-like flexible and rigid FWMAVs may differ significantly from each other, and when the flight speed is less than 3.0 m/s, using flexible wings is favorable, as they help the FWMAV reduce the power requirement and stabilize the lateral dynamics.
41 citations
TL;DR: This work uses experimental data to optimize the flapping wing structure for maximum thrust production in hover mode and applies a surrogate-based optimization algorithm called Efficient Global Optimization with different sampling criteria and multiple surrogates.
Abstract: Flapping wing micro air vehicles are capable of hover and forward flight with high maneuverability. However, flapping wing flight is difficult to simulate accurately because it is a more complex phenomenon than fixed wing or rotorcraft flight. Consequently, the optimization of flapping wing behavior based on simulation is limited and, therefore, we have elected to optimize a wing experimentally. Specifically, we use experimental data to optimize the flapping wing structure for maximum thrust production in hover mode. We point out the similarities or otherwise between experimental optimization and the more common simulation-based optimization. Experimental optimization is hampered by noisy data, which is due to manufacturing variability and testing/measurement uncertainty in this study. These uncertainties must be reduced to an acceptable level and this requires their quantification. Therefore, improvements in manufacturing and testing procedures were implemented to reduce the noise. Another challenge is to limit the number of experiments for reducing time and cost. This is realized by using surrogates, or meta-models, to approximate the response (in this case, thrust) of the wing. In order to take into account the uncertainty, or noise, in the response, we use a Gaussian Process surrogate with noise and a 2nd order polynomial response surface. We apply a surrogate-based optimization algorithm called Efficient Global Optimization with different sampling criteria and multiple surrogates. This enables us to select multiple points per optimization cycle, which is especially useful in this case as it is more time efficient to manufacture multiple wings at once and this also serves as insurance against failed designs.
37 citations
TL;DR: In this article, a 2D unsteady aerodynamic model based on potential flow theory has been extended for a flexible flapping wing of variable camber versus a rigid one, and the modified UAM is then validated by comparing with CFD results of a typical insect-like flapping motion from previous research.
27 citations
References
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05 Feb 2001
TL;DR: In this article, a modern treatment of the subject, both the theory of inviscid, incompressible, and irrotational aerodynamics and the computational techniques now available to solve complex problems is presented.
Abstract: Low-speed aerodynamics is important in the design and operation of aircraft flying at low Mach number, and ground and marine vehicles. This 2001 book offers a modern treatment of the subject, both the theory of inviscid, incompressible, and irrotational aerodynamics and the computational techniques now available to solve complex problems. A unique feature of the text is that the computational approach (from a single vortex element to a three-dimensional panel formulation) is interwoven throughout. Thus, the reader can learn about classical methods of the past, while also learning how to use numerical methods to solve real-world aerodynamic problems. This second edition has a new chapter on the laminar boundary layer (emphasis on the viscous-inviscid coupling), the latest versions of computational techniques, and additional coverage of interaction problems. It includes a systematic treatment of two-dimensional panel methods and a detailed presentation of computational techniques for three-dimensional and unsteady flows. With extensive illustrations and examples, this book will be useful for senior and beginning graduate-level courses, as well as a helpful reference tool for practising engineers.
1,810 citations
TL;DR: The basic physical principles underlying flapping flight in insects, results of recent experiments concerning the aerodynamics of insect flight, as well as the different approaches used to model these phenomena are reviewed.
Abstract: The flight of insects has fascinated physicists and biologists for more than a century. Yet, until recently, researchers were unable to rigorously quantify the complex wing motions of flapping insects or measure the forces and flows around their wings. However, recent developments in high-speed videography and tools for computational and mechanical modeling have allowed researchers to make rapid progress in advancing our understanding of insect flight. These mechanical and computational fluid dynamic models, combined with modern flow visualization techniques, have revealed that the fluid dynamic phenomena underlying flapping flight are different from those of non-flapping, 2-D wings on which most previous models were based. In particular, even at high angles of attack, a prominent leading edge vortex remains stably attached on the insect wing and does not shed into an unsteady wake, as would be expected from non-flapping 2-D wings. Its presence greatly enhances the forces generated by the wing, thus enabling insects to hover or maneuver. In addition, flight forces are further enhanced by other mechanisms acting during changes in angle of attack, especially at stroke reversal, the mutual interaction of the two wings at dorsal stroke reversal or wing-wake interactions following stroke reversal. This progress has enabled the development of simple analytical and empirical models that allow us to calculate the instantaneous forces on flapping insect wings more accurately than was previously possible. It also promises to foster new and exciting multi-disciplinary collaborations between physicists who seek to explain the phenomenology, biologists who seek to understand its relevance to insect physiology and evolution, and engineers who are inspired to build micro-robotic insects using these principles. This review covers the basic physical principles underlying flapping flight in insects, results of recent experiments concerning the aerodynamics of insect flight, as well as the different approaches used to model these phenomena.
1,182 citations
TL;DR: In this article, a review of the recent progress in flapping wing aerodynamics and aeroelasticity is presented, where it is realized that a variation of the Reynolds number (wing sizing, flapping frequency, etc.) leads to a change in the leading edge vortex (LEV) and spanwise flow structures, which impacts the aerodynamic force generation.
877 citations
TL;DR: In this paper, finite element incremental formulations for non-linear static and dynamic analysis are reviewed and derived starting from continuum mechanics principles, and a consistent summary, comparison, and evaluation of the formulations which have been implemented in the search for the most effective procedure.
Abstract: SUMMARY Starting from continuum mechanics principles, finite element incremental formulations for non-linear static and dynamic analysis are reviewed and derived. The aim in this paper is a consistent summary, comparison, and evaluation of the formulations which have been implemented in the search for the most effective procedure. The general formulations include large displacements, large strains and material non-linearities. For specific static and dynamic analyses in this paper, elastic, hyperelastic (rubber-like) and hypoelastic elastic-plastic materials are considered. The numerical solution of the continuum mechanics equations is achieved using isoparametric finite element discretization. The specific matrices which need be calculated in the formulations are presented and discussed. To demonstrate the applicability and the important differences in the formulations, the solution of static and dynamic problems involving large displacements and large strains are presented.
789 citations
Book•
01 Jun 1959
TL;DR: Theory of wing sections, including a summary of airfoil data, is discussed in this article, where the authors also present a theory of wing section sections, and the analysis of the data.
Abstract: Theory of wing sections, including a summary of airfoil data , Theory of wing sections, including a summary of airfoil data , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
621 citations